Top down is having the leadership develop the plan, and the push it down to those below them on the org chart. Basically the military model.

Bottom up is engaging the opinions and input to lower levels of an organization, soliciting participation from all levels of an organization, and then using all the information to make more informed decisions at the top leadership levels.

Top down can be quick, simple, easy, and usually requires significant amounts of organizations change management to execute; because the people making the strategy happen have no idea what’s going on.

Bottom Up takes longer, requires analysis and synthesis, requires compromise and strong leadership to make decisions on conflicts, but is usually easier to execute if done in good faith because all levels of the organization were part of the planning process and already know who, what, why, where, how, and most importantly already have skin in the game.

From a Design Perspective – not necessarily strategy, but engineering

Top Down is saying we need a Car, or a web site, and then figuring out all the details. Starting with the “Big Picture” and then drilling down.

Bottom up is coming up with a list of specifications or requirements, and then connecting the dots, figuring out how they fit together and what the cohesive whole looks like.

Top Down is a good way to focus systems integration and design variations – you know what the end product is supposed to be. Helpful for building physical things that are hard to iterate or modify (like ships, buildings, bridges)

Bottom up is a good way to hit minimum viable product. You may not know what the end result is supposed to be (or will be), but you start with a series of features and go from there. Is a nice option for operational processes or software startups that just need something that works, and it’s easy to modify and add to it as you go.

Strategic Example of the two different approaches when making dinner:

Top down approach could be to decide you are making chicken and rice, and then get the ingredients to make chicken and rice.

Top down approach could be to order Pizza (leaving you an option for bottom up discussion on Pizza toppings).

Bottom up approach could be to check the refrigerator, cupboards, and pantry, and cook what you find.

Bottom up approach could be to ask your roommates or family what they want for dinner and try to compromise between everyone’s ideas and what’s available.

Strategically you are best off having a plan set up long before you get hungry, so when people start asking what’s for dinner, you simply hand them a hot plate of something they typically enjoy – i.e. Taco Tuesday, Spaghetti Wednesday. A predictable routine will help manage everyone’s expectations, and make it easier to changes plans proactively (you have a plan to change).